Hectograph blanket and method of preparing same



Patented Sept. 10, 194d HECTOGRAPH BLANKET AND METHOD OF PREPARDNG SAME Robert C. Bour, Chicago, Ill., assignor to Ditto, In-

corporated, Chicago, 111., a corporation of West Virginia No Drawing. Application February 13, 1942, Serial No. 430,742

3 Claims. 1

The invention relates to hectograph blankets and to methods of preparing the same.

A hectograph blanket comprises a hydrophilic copy mass such as a gelatine gel which is generally secured to a backing by means of a bonding layer. A drying oil such as linseed oil is ordinarily used as a bonding agent but other bonding agents may be used.

In the manufacture of hectograph blankets the difficulty known as depressions is frequently encountered. These depressions consist of spots on which the hectograph mass has failed to cover the backing so that deep pits remain in the finished product.

I have made a study of the cause of depressions and believe that they are mainly caused by the presence of small amounts of fatty material either in the hectograph compositions or on the backing, or by insufficient drying or excessive content of fatty material in the bonding agents employed. Since these factors are diflicult to control with accuracy, depressions will occur at times in spite of rigid precautions and result in considerable loss to the manufacturer of hectograp-h blankets.

An object of this invention is therefore to provide a hectograph blanket which is substantially free from depressions.

Another object is to provide a means for rendering a hectograph composition substantially insensitive to depression forming influences.

I have discovered that the incorporation of a cation active material, or particularly a cation active wetting agent, in the fluid hectograph composition which is to be applied to a backing makes it possible to apply the composition to a backing which even contains greasy material or is not entirely free therefrom and produce a hectograph copy mass without the formation of depressions.

I have also discovered that hectograph copy masses containing these cation active wetting agents are non-reactive with the basic dyes used in hectograph duplication, whereas such basic dyes react with anionic wetting agents. Furthermore, the cationic wetting agents are generally non-tanning and therefore do not cause objectionable tanning of the copy mass.

The cation active materials which are employed in this invention consist essentially of a long chain aliphatic residue attached to a radical capable of ionizing in a solution in such a way that a positive charge is assumed by the long chain structure of the molecule. The long chain preferably consists of any hydrocarbon structure of eight carbon units and preferably those of at least twelve. This chain structure may exist as aryl-alkyl, alkyl-aryl-alkyl or alkyl-alkyl combinations which, contrary to ordinary anionic soap or soaplike compounds, results in assuming a'positive charge in aqueous solutions when having a hydrophilic negative head such as sulphoniiun, phosphonium, halogen, etc. As examples of typical suitable compounds are stearyl trimethyl am-- monium bromide, lauryl trimethyl ammonium bromide, cetyl pyridinium bromide, cetyl dimethyl sulfonium methyl sulfate, cetyl tetramethyl ammonium bromide, dodecyldimethyl ammonium methyl sulfate, phenyl benzyl dimethyl ammonium chloride, and sodium octyl tripolyphosphate.

The quaternary ammonium salts are suitable cation active wetting agents. A quaternary ammonium salt which has been found particularly suitable is cetyl dimethyl benzyl ammonium chloride, which is known to the trade as Triton K-B-ll, manufactured by Rohm and Haas Co.

Other cation active materials which have been found very effective are the sodium octyl tripolyphosphates such as those having the approximate formula Na5[CI-I3(CI-Iz)6CI-I2]tPsO2o. One type of these materials is known to the trade as Victor wetting agents -3 and 58, marketed by the Victor Chemical Works.

The cation active materials may be used in the hectograph composition in very small amounts such as amounts of the order of one-tenth of 1% of the total hectograph mass. Larger amounts are not objectionable and may be used but generally produce no advantage beyond that obtainable by the use of one-tenth of 1%.

While there have been shown and described certain embodiments of the invention, it is to be understood that it is capable of many modifications. Changes, therefore, may be made without departing from the spirit and scope of the invention as described in the appended claims, in which it is the intention to claim all novelty inherent in the invention as broadly as possible, in view of the prior art.

I claim:

1. A hectograph blanket comprising a hydrophilic gelatinous copy mass, a backing and an intermediate bonding agent of the drying oil type, said copy mass containing a cation active wetting 'agent consisting essentially of a long chain ali- 

